Ligand Substitution Reactions of Transition Metal Organometallic Complexes and Homogeneous Catalysis

Transition metal organometallic homogeneous catalysts depend on the ease of ligand substitution in one or more of the catalytic steps. Thus, it follows that the more we learn about the factors which affect rates of ligand substitution, the better we will be able to design useful catalysts. Three different types of approaches to the enhancement of ligand substitution are discussed. These are (1) through the use of spectator ligands which permit an 18‐electron system to react by an associative process, (2) the relative rates of substitution of a 17‐electron and a corresponding 18‐electron system, and (3) the reactivity order 1st row < 2nd row > 3rd row transition metals for a given metal triad. Specific examples are given for each of these approaches to generate more substitution labile organometallic compounds.